Traditionally, compressors for commercial refrigeration have been sized with cooling capacities sufficient for the greatest system load they will encounter (i.e., pull down in a refrigerator application). But because loads vary widely with the seasons, and even from hour to hour, the compressor sized for the maximum load turns out to be oversized for long periods.
On average, commercial systems run partially loaded about 65 percent of the time, delivering full capacity for short periods and then shutting down.